Psychological Medicine

Original Articles

Is executive impairment associated with schizophrenic syndromes? A meta-analysis

C. R. M. Dibbena1, C. Ricea2, K. Lawsa3 and P. J. McKennaa4a5 c1

a1 Fulbourn Hospital, Cambridge, UK

a2 Institute of Psychiatry, De Crespigny Park, Denmark Hill, London, UK

a3 School of Psychology, University of Hertfordshire, Hatfield, UK

a4 Benito Menni CASM, Barcelona, Spain

a5 CIBERSAM, Spain

Abstract

Background A key neuropsychological proposal in schizophrenia is that negative and disorganization symptoms are associated with different patterns of impairment on executive tasks.

Method Studies reporting correlations between positive, negative or disorganization symptoms and any type of executive test were meta-analysed. The influence of moderating factors was also examined, including age, treatment and stage of illness and whether symptoms were relapsing or persistent. The magnitudes of the correlations were compared with those for general intellectual impairment.

Results Pooled correlations between executive impairment and both negative symptoms and disorganization were significant in the small-to-moderate range. That for positive symptoms (‘reality distortion’), however, was close to zero. The pattern of correlations among different executive tests differed significantly for negative symptoms and disorganization. Patients with stable clinical pictures showed significantly higher correlations with executive impairment than those with relapsing and remitting illnesses. Both negative symptoms and disorganization also correlated significantly with general intellectual function as indexed by current IQ.

Conclusions Meta-analysis supports the view that negative symptoms and disorganization are associated with partially dissociable patterns of executive impairment. However, co-existent general intellectual impairment has been an important confounding factor in the studies to date.

(Received September 27 2007)

(Revised April 28 2008)

(Accepted May 08 2008)

(Online publication June 30 2008)

Correspondence

c1 Address for correspondence: Dr P. J. McKenna, Benito Menni Complex Assistencial en Salut Mental, Germanes Hospitalàries del Sagrat Cor de Jesús, C/Doctor Antoni Pujades 38-C, 08830 Sant Boi de Llobregat, Barcelona, Spain. (Email: mckennapeter1@googlemail.com)

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